The Western Robin 
recognition of P. m. caurinus, a resaturated form from Vancouver Island and broadly 
contiguous mainland territory, has made us aware that resident birds of the Southwest 
are really lighter-breasted. 
Moreover, the presence of white in the tail of certain western birds is scarcely the 
casual factor we had thought. Variable this character undoubtedly is, but its decided 
presence is never found in southwestern breeding birds. The case seems, rather, to be 
analogous to that of the Dendroica auduboni-coronata group: The more aggressive 
eastern form passing in a northwesterly direction (along the line of the retreating 
ice-sheet?), has long since outstripped its western rival in the race to northwestern 
Alaska. Now instead of following the ancestral line of autumnal retreat through 
Saskatchewan and Manitoba, P. m. migratorius, like D. c. coronata, has begun to cut 
“cross-lots,” and even to go straight south (like D. c. hooveri) in search of a winter home. 
At an}' rate, I so construe the presence in winter of certain of our white-tailed dark¬ 
breasted birds which are found in Californian collections.] 
Addendum. —At the earnest representation of Mr. H. S. Swarth, and since 
there is not time to review the evidence upon the eve of going to press, I am bracketing 
the treatment of the Eastern Robin. Mr. Swarth holds that all “wh'te-cornered” birds 
in California are to be accounted for by indhidual variation in P. m. propinquus. 
He may be right, and I am willing that the foregoing treatment should be regarded as an 
expanded “hypothetical'' out of place; but 1 am quite confident that Mr. Bowles and I 
hare encountered flocks of pure P. m. migratorius stock, during the migrations, in 
western Washington. They may have cut in at a point further north, but the theory 
of a Californian flight line deserves consideration. 
No. 150a Western Robin 
A. O. U. No. 761a. Planesticus migratorius propinquus (Ridgway). 
Description. —Similar to P. migratorius, but white on inner web of outer 
rectrices much reduced, or wanting; gray of upperparts grayer and more olivaceous, 
more sharply contrasting with black of head; cinnamon-rufous of underparts averaging 
paler; wing, tail, and tarsus slightly longer. In winter upperparts more distinctly 
tinged with olivaceous. Length of males about 260.3 (10.25); wing 140 (5.52); tail 105 
(4.13); bill 20.3 (.80); tarsus 34.1 (1.34). Females slightly smaller. 
Recognition Marks. —“Robin” size; cinnamon-rufous below—everyone knows 
the Robin—without white on “corners” of tail, as distinguished from P. m. migratorius. 
Nesting. — Nest: A thick-walled but shapely bowl of mud (rarely, felted vegetable 
fibers instead), set about with twigs, leaves, string, and trash, and lined with fine 
grass-stems; placed anywhere in trees, or variously, but usually at moderate heights. 
Eggs: 3 or 4, rarely 5; bluish green (niagara green to light niagara green), unmarked. 
Av. of 21 eggs from Eureka 27.9 x 20.6 (1.10 x .81); index 73. Season: April 15-July 
10; two broods. 
Range of P. m. propinquus. —Western United States, Mexico, and southern 
British Columbia (interiorly). Breeds from southern British Columbia and central 
Montana south to southern California, Jalisco, Oaxaca, and Vera Cruz, and from the 
western borders of the Great Plains west to the Pacific, save in the extreme northwest 
humid coastal district. Winters irregularly in regions of milder temperatures, practi¬ 
cally throughout its range, and south to highlands of Guatemala. 
Distribution in California. — Probably largely resident within the State: in 
summer at the upper levels; in winter irregularly but abundantly at the lower levels. 
Breeds in Boreal and Transition zones throughout the Sierras, and at lower levels 
759 
